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BOARD REVIEW DH227 RADIOLOGY LISA MAYO, RDH, BSDH

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BOARD REVIEW DH227RADIOLOGY

LISA MAYO, RDH, BSDH

Radiation Discovery

Wihelm Conrad Roentgen: 1985X-ray: unknown natureDiscovered when experimenting with a

cathode ray tube 1st dental radiograph: 1896

Fundamental of Radiation Radiation

Emission & propagation of energy through space

Particulate RadiationTiny particle of matter that possess mass &

travel in straight lines at high speedsElectrons, beta particles, cathode rays,

protons, alpha particles, neutrons

Fundamental of Radiation Electromagnetic Radiation

Propagation of wave-like energy (w/out mass) through space or matter

X-rays, cosmic rays, UV rays, visible light, infrared light, radar waves, microwaves, radio waves

Vary in energyIonizing vs non-ionizingBelieved to move through space as both a

particle (photon) and a wave (next slide)

Light Spectrum

Fundamentals of Radiology Left of Visible Light

Longer wavelengths

Lower frequencies

Right of Visible Light: x-raysShorter wavelengths: resulting from tungsten target

being hit with accelerated e- in a vacuum

Higher frequencies

Fundamental of Radiation Wave Concept

Velocity: speed of a wave = speed of lightWavelength: distance between one crest of

one wave and the crest of the next○ Determines the energy and penetrating power○ Shorter wavelength, higher the energy, more

penetrating (harder) the beamFrequency: # wavelengths that pass a given

point in a certain amt of time

WavelengthDefinition: distance in a periodic wave between 2

points of corresponding phrasesFrequency: # of crests that pass per unit of time

Fundamentals of Radiation

http://www.youtube.com/watch?v=iNcKT4uJZBY

Fundamentals of Radiation

Light: wave or a stream of particles?Age old-debateExhibits characteristics of bothParticle: Isaac NewtonWave: Maxwell’s Theory of

ElectromagnetismDescribes wave-like properties of all

electromagnetic radiation

Electromagnetic RadiationProperties expressed best by:

1. Wave Theory

2. Quantum Theory

Fundamentals of Radiation

WAVE THEORY

Electromagnetic RadiationWave Theory

○ How radiation propagated in the form of waves○ Useful when considering radiation in bulk when

millions of quanta are being examined

Electric & magnetic fields orientated in planes at right angles to one anotherOscillate perpendicular to the direction of motion

Fundamentals of Radiation

Electromagnetic Radiation Quantum Theory

○ Electromagnetic energy described as bundles of energy called photons

○ Successful in correlating experimental data Interaction of radiation with atomsPhotoelectric effect Production of x-rays

Fundamentals of Radiation

Fundamental of Radiation Ionization

Most atoms are neutral○ # protons = # electrons

Ion: atom gains or loses an electronAtoms loses an electron, an ion pair results

○ Proton = (+)○ Electron= (-)

Ionizing Radiation: radiation that is capable of producing ions

Fundamentals of Radiation

Photon Elementary particle responsible for electromagnetic

phenomenaCarrier of electromagnetic radiation of all

wavelengths (gamma, x-ray, UV, visible, infrared, microwave, radio)

Differs from electron & quark in that it has zero rest mass

Travels in a vacuum & at the speed of lightHas both wave and particle properties

Fundamental of Radiation Primary Radiation

X-ray beam that exists the tubehead Secondary Radiation

X-radiation that is created when the primary beam interacts w/matter

Scatter RadiationForm of secondary radiationX-ray that has been deflected from its path by the

interaction w/matter Interaction of X-Radiation

X-ray can pass through the patientX-ray can be completely absorbed by patientX-ray can be scatteredX-ray can be transmitted

Light can have 4 fates when hits tissue 1. Absorbed

Primary & beneficial effect of laser energy 2. Reflected

Beam redirecting itself off the surface, no effect on tissueEx: Caries-detecting laser

3. Scattered May harm surrounding structures

4. Transmitted May harm surrounding structuresLaser energy directly through tissues

Fundamental of Radiation Bremsstrahlung Radiation

Produced by sudden slowing or speeding of e- towards a target

Primary source of x-raysNegatively charged e- directed towards a (+)

charged source → loss of velocity occursGenerate continuous spectrum of photons

Characteristic RadiationOnly a minor source of radiation e- from filament displaces an e- from a shell of

tungsten target atom – atom ionizes

NBQ

A radiograph produced from the movement of an electron from an outer shell to a vacancy in an inner shell is referred to as:

a. Thomson scatter

b. Bremsstrahlung radiation

c. Characteristic radiation

d. Particulate radiation

NBQ

A radiograph produced from the movement of an electron from an outer shell to a vacancy in an inner shell is referred to as:

a. Thomson scatter

b. Bremsstrahlung radiation

c. Characteristic radiation

d. Particulate radiation

Properties of X-Rays Characteristics: invisible, no mass, no weight Travel: in a straight line, at the speed of light Wavelengths

Have shorter wavelengths, high frequencyHard x-rays: short, high penetrationSoft x-rays: longer less penetrating, more likely to be

absorbed into the tissues Penetration: pass through matter or absorbed by

matter, depending on atomic structure of matter Produces: an image on photographic film Causes: ionization Distance: lose intensity with distance

Image Characteristics

Detail/Resolution/DefinitionOver sharpness of imageCalled “radiographic definition”Relates to distinct and sharp demarcation of image

elementsFocal spot size: smaller = sharper imageFilm composition: smaller silver halide crystals= sharper

imageMovement of film or patient during exposure= less sharp

imageInfluenced by: BID length, type of films, use of intensifying

screens

Image CharacteristicsPenumbra (“fuzziness or un-sharpness”)

1. Source of radiation small• Small focal spot keep penumbra small• Lg focal spot ↑ penumbra

2. Source to object distance • Long SFD will ↓ penumbra, short SFD will ↑ penumbra

3. Object to film distance • Small object to film distance ↓ penumbra• ↑ source-to-film-distance will ↑ un-sharpness

4. Object and film parallel• Foreshorten or elongation

5. Source perpendicular to object and film

Image Characteristics

Sharpest image w/ least magnification1. Small focal spot

2. Short object-to-film-distance

3. Large target (source)-to-film-distance

4. Film and tooth parallel

5. Beam perpendicular to film

Image Characteristics

DensityOverall Darkness or LightnessMore photons = more densityInfluenced by: film type, processing, exposure

time. mA settings, BID length, kVp setting, source to object distance

ContrastVariations of gray and between white and blackHow sharply dark and light areas are separatedInfluenced by: patient size, film type, processing,

film storage, MAINLY kVp setting

Image Characteristics High contrast/Short Scale

Few shades of gray, mostly black and whitesHigh visual contrastProduced by low kVp settingsLess than 75kVp

Low contrast / Long ScaleMany shades of grayLow visual contrastProduced by high kVpSettings higher than 80kVp

Factors Tubehead Film Density Film Contrast

mA ↑ # photons ↑ density

Exposure Time ↑ # photons ↑ density

kVp ↑ # photons↑ penetration

↑ density Long scale, many grays, low visual contrast

Aluminum ↓ #photonsRemove weak photons

↓ density Long scale, many grays, low visual contrast

Distance Increase

↓ # photons ↓ density

Image Characteristics

RadiolucentPortion of a processed radiograph that is

dark or blackThings that permit the passage of x-raysAir space, soft tissue

RadiopaquePortion of a processed radiograph that is

light or whiteStructures that absorb x-raysEnamel, dentin, bone, metals

Image Characteristics

MagnificationImage appears larger than the actual size of

the object it representsDecrease object-film distance decrease

magnification (tooth close to film)Increase target-to-film distance decrease

magnification (use a longer PID or cone)

Image Characteristics Distortion

Variation in the true size and shape of the object being radiographed

May be unequal magnification of different parts of the same object

Results from improper film alignment or angulation of the x-ray beam

To minimize distortion:○ Object and film must be parallel○ X-ray beam must be directed perpendicular to the

tooth and filmCan cause: Elongation & Foreshortening

Image CharacteristicsPrinciples of Shadow Casting

Geometric Characteristics

Influencing Factors Effect of Influencing Factors

Result

Sharpness Focal spot sizeFilm compositionMovement

↓ focal spot↓ crystal size↓ movement

↑ sharpness↑ sharpness↑ sharpness

Magnification Target-film distanceObject-film distance

↑ target-film dist.↓ object-film dist.

↓ magnification↓ magnification

Distortion Object-film alignment

X-ray beam alignment

Object & film parallelBeam perpend. To object & film

↓ distortion

↓ distortion

DEFINITIONS Attenuation: process where radiation loses power as it travels

through matter. (Removal of x-ray photons) As the energy of radiation ↑, the # of photons passing through

matter ↑ As density, atomic #, electrons per gram of the material ↑, the # of

photons passing through the matter ↓ Elongation

Central ray not perpendicular to object Object and film not parallel Insufficient vertical angulation

Foreshortening Central ray not perpendicular to films Object and film not parallel Excessive vertical angulation

ElongationForeshorten

NBQ

Both milliampere and exposure time determine the

a. Degree of film fog

b. Number of x-rays produced

c. Energy of the radiation produced

d. Amount of scattered radiation produced

NBQ

Both milliampere and exposure time determine the

a. Degree of film fog

b. Number of x-rays produced

c. Energy of the radiation produced

d. Amount of scattered radiation produced

NBQ

Which of the following describes a radiographic film that has many graduations of gray from totally white to totally black?

a. Overexposed

b. Underexposed

c. Low contrast

d. High contrast

NBQ

Which of the following describes a radiographic film that has many graduations of gray from totally white to totally black?

a. Overexposed

b. Underexposed

c. Low contrast

d. High contrast

NBQ

Sharpness of the radiographic image is increased by

a. Using a smaller focal spot

b. Decreasing the focal spot-object distance

c. Decreasing the mA

d. Increasing the object-film distance

e. Using screen-film technique

NBQ

Sharpness of the radiographic image is increased by

a. Using a smaller focal spot

b. Decreasing the focal spot-object distance

c. Decreasing the mA

d. Increasing the object-film distance

e. Using screen-film technique

X-RAY MACHINE Glass vacuum tube

All air removedSurrounds electrodes of x-ray tube to provide a

vacuumThe aperture or window: thin segment of the glass

that allows maximum emission of x-rays and minimum absorption by the glass

Leaded glass housingPrevents x-rays from going in all directions

X-RAY MACHINECathode (-)

Serves as the source of e- to be directed at anodeComposed of:

○ Filament (tungsten wire): Filament that lies in a focusing cup: heated to give off e- (thermionic emission)

○ Focusing cup: e- from focusing cup are directed to focal spot

○ mA control regulates

1. Step-down transformer

2. Heating of the filament

3. Quantity of electrons “boiled off” during thermionic emission

○ Because charges repel – the electron beam is directed to a small area on the anode

X-RAY MACHINE

Anode (+)Composed of:

○ Tungsten target (high atomic #) in a ○ Copper stem (remember tungsten & copper) that

functions to conduct heat away from the target○ Focal spot: portion of a target bombarded by electrons

Convert e- from filament into photonsKilovoltage control regulates the:

○ Step-up transformer○ Voltage between the cathode and the anode○ Accelerating potential (speed) of electrons

X-RAY MACHINE

Focal Spot Sharpness of radiograph ↑as size of radiation

source ↓Heat ↑ as focal spot ↓in size

Power SupplyOhm’s Law: Volts = Amperes (I) x Resistance(R)

(electrical potential) (rate of e- flow)

Voltage = kVp. Describes the potential differences between the (-) and (+) and therefore, the speed or force of the moving e-toward the (+) charge

XRAY MACHINEPower Supply: Transformer (changes potential difference of incoming electrical energy to any desired level)

1. Provide low-Volt current to heat filament by use of step-down transformer Operation regulated by mA switch: adjusts R and

therefore current flow – regulates temp. of filament – Quality of x-rays

2. Step-up transformer Increases the voltage sufficiently to propel

electrons across the vacuum tube circuit to produce x-ray energy

3. Generate high difference between anode/cathode Controlled by kVp dial - selects varying V – controls

V between anode & cathode ↑ V = ↑ speed e- toward anode

X-RAY MACHINE

PID: Position-indicating devise○ An open ended, circular or rectangular “cone” that

extends from the tube head toward the image receptor

○ Fed regs: 7cm/2.75in diameter○ Length that ↑ focal-to-object distance creates a less

divergent beam○ Use fastest image receptor system: “F” speed

intraoral film requires the least amt of radiation to produce a diagnostic image

○ Longer PID = produce x-ray beam that is less divergentDecrease radiation exposureProvide better image resolution

NBQ

Federal guidelines limit the size of the intraoral x-ray beam at the client’s skin to:

a. 1 ¾ inches

b. 2 ½ inches

c. 2 ¾ inches

d. 3 ½ inches

e. 3 ¾ inches

NBQ

Federal guidelines limit the size of the intraoral x-ray beam at the client’s skin to:

a. 1 ¾ inches

b. 2 ½ inches

c. 2 ¾ inches

d. 3 ½ inches

e. 3 ¾ inches

NBQ

Which of the following position-indicating devises (cones) best minimizes the dose of radiation to the patient?

a. Pointed, plastic

b. Leaded, circular

c. Leaded, circular

d. Open-ended circular

e. Leaded, rectangular

NBQ

Which of the following position-indicating devises (cones) best minimizes the dose of radiation to the patient?

a. Pointed, plastic

b. Leaded, circular

c. Leaded, circular

d. Open-ended circular

e. Leaded, rectangular

NBQ

Use of which of the following causes unnecessary secondary radiation to the patient?

a. Speed D films

b. Plastic pointed cone

c. kVp under 70

d. Aluminum filtration over 2.0mm

e. Short (8”) target-to-films distance

NBQ

Use of which of the following causes unnecessary secondary radiation to the patient?

a. Speed D films

b. Plastic pointed cone

c. kVp under 70

d. Aluminum filtration over 2.0mm

e. Short (8”) target-to-films distance

FACTORS CONTROLLING XRAY BEAM

Exposure Time Tube Current (mA) Tube Voltage (kVp) Filtration Collimation

X-Ray Beam Quality

Exposure time: duration of x-ray production (quantity)

Distance: greater the distance, less x-ray reach film (quantity)

mA: regulates # e- and thus amt of x-ray produced (quantity)

kVp: regulates the energy or penetrating characteristics of the beam (quality)

↑ QUALITY

↑ KvP ↑Filtration ↑ Collimation ↑ Energy, speed of e-

↑Film density ↓ Contrast

X-Ray Beam Quality

Kilovoltage Peak (kVp, Voltage)Voltage is the difference between 2

electrical charges (cathode/anode)This difference determines the speed of e-

when traveling from cathode to the anode65-100 kVpDetermine the quality of x-ray production

(penetrating power)

↑ QUANTITY

↑mA ↑ Time ↑ kVp ↓Distance ↓ Collimation ↓ Filtration

X-Ray Beam Quantity Exposure Time

Interval of time x-rays are producedLonger exposure = more x-ray photonsLonger exposure = higher density60 impulses/second

mAThe ampere if the unit of quality of electric currentRegulates # e- travelling from cathode to anodeIncreased mA=more x-ray photonsIncreased mA=higher density

X-Ray Beam Quantity

Millampere-seconds (mAs)Both mA & exposure time have a direct

influence on # e- producesWhen combined, they form a factor termed

milliampere-secondsmAs = mA x exposure time (sec)

DistanceGreater distance from source of radiation (x-

ray tube) to x-ray film need more x-ray photons

X-Ray Beam Quantity

Inverse Square LawIntensity of radiation is inversely proportional

to the square of the distance from the source of radiation

Original intensity = New intensity____

New distance 2 = Original distance2

X-RAY MACHINE

FiltrationProcess of selectively removing x-rays from the

beamFilters low-energy, non-penetrating raysFederal regs:

○ 1.5mm of aluminum-equivalent filtration for units operating below 70kVp

○ 2.5mm for units operating above 70kVp

X-RAY MACHINE

CollimationProcess of restricting the size and shape of x-ray

beamAchieved by use of lead diaphragm disc w/ circular

or rectangular opening through which the beam is narrowed

Reduced scatter radiationReduce film fogging

NBQ

The focusing cup in an x-ray tube serves

a. To focus the electron beam

b. As the source of x-rays

c. As the source of electron

d. To focus the x-ray beam

e. Adjust the focal spot

NBQ

The focusing cup in an x-ray tube serves

a. To focus the electron beam

b. As the source of x-rays

c. As the source of electron

d. To focus the x-ray beam

e. Adjust the focal spot

XRAYS & BIOLOGY

X-ray photons are either 1. Absorbed: photons transfer energy to

patient

2. Scattered: photons change in direction

3. Transmitted: photons pass through pt unchanged

Dental x-rays cause 1. Coherent Scattering

2. Photoelectric Absorption

3. Compton Scattering

XRAYS & BIOLOGY

Review interactions of x-rays on humansEffects on oral tissuesEffects on FetusEffects on Total Body: Leukemia, Cancers,

Growth and Development, Gene MutationOsteoradionecrosis

Mandible Bone is destroyed (bone death) Brittleness

XRAYS & BIOLOGY

Radiation InjuryNot all x-rays reach the filmMany are absorbed by patient tissues

IonizationOccurs when x-rays strike patient tissuesMay have little effect on cells if the chemical

changes do not alter sensitive moleculesMay have a profound effect on structures of

great importance to cell function (DNA)

XRAYS & BIOLOGY Free radical formation

A molecule with a single, unpaired e- in its outermost shell

Results with reactive & unstable free radicalsThe ionization of water is the most common

mechanism of damage in humansFR – combine to form- toxins such as H2O2

Dose-response curve & radiation injuryWhat level of radiation is acceptable?No safe amt of radiation exposureDose-response curveCorrelates the damage (response) of tissues w/ amt

(dose) of radiation

XRAYS & BIOLOGY

Sources of radiation exposureNatural radiation

○ Background or environmental radiation○ Cosmetic, terrestrial, radon

Artificial radiation ○ Man-made○ Medical / dental, wristwatches, TV, smoke

alarms, airport security

XRAYS & BIOLOGY Radiographs during pregnancy

ER tx can be done anytime: prefer to avoid 1st trimester2nd trimester bestGenetic dose w/out lead apron

○ Men: 1/10,000○ Women: 1/50,000

Dental vs Background RadiationFMX = 2-4 days4BWX=8 hrsPanoramic = 8 hrs

XRAYS & BIOLOGY

Radiation injury sequence, repair, accumulation1. Latent period: time from exposure to radiation

and appearance of clinical signs

2. Period of injury

3. Recovery period: cellular damage can repair to a certain extent

4. Cumulative effects: effects of radiation exposure are additive

XRAYS & BIOLOGY

Somatic & Genetic EffectsSomatic cells

○ Cells in the body except the reproductive cells○ If effected produce poor health (cataracts,

cancer, etc..) but not transmitted to future generations

Genetic cells○ Reproductive cells (ova, sperm)○ Effects not seen in the person irradiated, but

are passed to future generations

XRAYS & BIOLOGY

Radiation effects on cellsCells may be resistant to radiationCells may be sensitive to radiationDetermined by:

○ Mitotic activity: cells that divide frequently more sensitive

○ Cell differentiation: immature cells are more sensitive

○ Cell metabolism: cells w/high metabolism are more sensitive

XRAYS & BIOLOGY

High sensitivityReproductive tissue, lymphoid system, bone

marrow, intestines, mucous membranes Medium sensitivity

Fine vasculature, growing cartilage/bone, salivary glands, lungs, kidneys, liver

Low sensitivityNerve tissue, skeletal muscle, heart, optic

lens, mature bone

XRAYS & BIOLOGY

Tissue & Radiation EffectHematopoietic (blood-forming)ReproductiveThyroidSkinEyesLeukemiaMutationsCarcinomaCataracts

NBQ

Arrange the following cells and tissues from MOST SENSITIVE to LEAST SENSITIVE to ionizing radiation

1. Adult bone and nerve

2. Epithelium and muscle

3. Alimentary tract and immature bone

4. Blood-forming cells and reproductive cells

 

a. 1, 4, 2, 3

b. 4, 1, 2, 3

c. 4, 2, 3, 1

d. 4, 3, 2, 1

NBQ

Arrange the following cells and tissues from MOST SENSITIVE to LEAST SENSITIVE to ionizing radiation

1. Adult bone and nerve

2. Epithelium and muscle

3. Alimentary tract and immature bone

4. Blood-forming cells and reproductive cells

 

a. 1, 4, 2, 3

b. 4, 1, 2, 3

c. 4, 2, 3, 1

d. 4, 3, 2, 1

XRAYS & BIOLOGY Short & Long-Term Effects

Short-term effects○ Assoc w/ large amts radiation○ Nausea, vomiting, diarrhea, hair loss,

hemorrhageLong-term effects

○ Small amts radiation over long period○ Cancer, birth abnormalities, genetic

defects

XRAYS & BIOLOGY Oral effects of radiation

Short-term effects○ Erythema, mucositis○ Ulcers, dermatitis

Long-term effects○ Loss of taste, xerostomia○ Radiation caries, candidiasis○ Possible development of osteoradionecrosis

RADIATION PROTECTION

16in Target-to-film distance 16cm Source-2-skin distance 2.75in Collimation (beam on pt’s

face) Max Permissible Dose (MPD)

Occupational and non-occupational radiation exposure

Old units and new – learn both! (next slide)

RADIATION PROTECTIONMeasurement Old Units S.I. Units

Exposure to air Roentgen Coulomb/Kg

Absorbed dose Rad Gray (Gr)

Dose equivalent in man Rem Sievert (Sv)

Old MPD Occupational 5 rem/yr400 mrem/mo100 mrem/wk

Old MPD Non-Occupational 0.5rem/yr

New MPD Occupational 6.2 Sv/yrNew MPD Non-Occupational 0.005 Sv/yr

RADIATION PROTECTION Filtration

Aluminum discsFilter out long wavelength, low energy x-rays, low

penetrating x-raysTotal filtration > 70kVp = 2.5mm of AluminumTotal filtration ≤ 70kVp = 1.5mm of Aluminum

CollimationRestricts the size and shape of beamLead plate w/ central holeRound or rectangularFederal regulations: x-ray beam < 2.75in @ skin

Position Indicating Devise8in (short)16in (long) < volume of tissue is irritated < scatter

RADIATION PROTECTION Thyroid collar Lead apron

Absorbs 90% of the scatter radiation that would have reached the reproduction tissues

Lead equivalent = 0.25mm Fast film

Film speed determines how much radiation and how much exposure time are necessary to produce an image on a film

Using a fast film is the most effective method to reduce radiation exposure

RADIATION PROTECTION

Films speedDetermines how much radiation and how

much exposure time are necessary to produce a image on a film

A speed (slowest) – F speed (fastest)Speed doubles w/ each letter

○ B twice as fast as A○ C 4x as fast as A

NBQ

With all other technique factors remaining constant, an increase in film speed will:

a. Increase image density

b. Decrease image density

c. Increase image contrast

d. Decrease image contrast

e. Have no effects on the image

NBQ

With all other technique factors remaining constant, an increase in film speed will:

a. Increase image density

b. Decrease image density

c. Increase image contrast

d. Decrease image contrast

e. Have no effects on the image

NBQ

Using an “E” speed group film rather than a “D” speed group film to produce a radiograph requires

a. A longer exposure time

b. A shorted exposure time

c. A decreased developing time

d. An increased developing time

NBQ

Using an “E” speed group film rather than a “D” speed group film to produce a radiograph requires

a. A longer exposure time

b. A shorted exposure time

c. A decreased developing time

d. An increased developing time

NBQ

Using an “E” speed group film rather than a “D” speed group film to produce a radiograph requires

a. A longer exposure time

b. A shorted exposure time

c. A decreased developing time

d. An increased developing time

RADIATION PROTECTION

Intensifying screensUsed in extraoral radiographyReduce exposure time & amt radiation a

patient receives ALARA

All exposure to radiation must be kept to a minimum

“As low as reasonably achievable”

FILM PROCESSING Film Composition

Film base: flexible piece of plasticAdhesive layer: attaches emulsion to film baseFilm emulsion

○ Gelatin: suspends silver halide crystals○ Silver halide crystals: sensitive to radiation

Protective layer Latent Image Formation

Silver halide crystals absorb x-ray and store the energy

Various amts of stored energyInvisible pattern of stored energy: Latent Image

FILM PROCESSING

Film sizesSize 0: BWX/PA in small childrenSize 1: PA’s adult teeth, BWX in kidsSize 2: PA’s adult teeth, BWX in adultsSize 3: BWX’s only. Longer, narrower than

size 2 (shows all post teeth)Size 4: occlusal films

FILM PROCESSING

Extraoral FilmsPanoramic: shows wide viewCephalometric: shows facial profileIntensifying screens

○ Intensify the effect of x-rays on film○ Less radiation is required

FILM PROCESSING

Manual1. Development

2. Rinsing: removes developer

3. Fixation

4. Washing: removes excess chemicals

5. Drying

FILM PROCESSING Developer

Precipitate all of the silver in those silver halide crystals that contain a latent image speck

Swell and soften the emulsion of the filmHydroquinone & Elon5min at 68°

FixerRemove the undeveloped/unexposed silver halide

crystals from emulsionShrink and re-harden the emulsion of the filmSodium thiosulfate & ammonium thiosulfate10min (2x development time)

FILM PROCESSINGDEVELOPER (reduce) FIXER (clear)

Solvent: H2O (soften film emulsion) Solvent: H2O

Preservative: Na-sulfite (protects from oxidation)

Preservative: Na-sulfite (protects from oxidation)

Reducing agents:Phenidone/Elon (older version is Elon) (bring out gray)Hydroquinone (bring out contract)

Clearing agent:Ammonium triosulfate

Activator: alkaline pH Speeds up reducing process

Acidifier: acetic acid (low pH = 4.5)

Restrainer: Na, K, Br (anti-fog agents) Hardening agent: AlK-sulfate, CrK-sulfate, K alum

FILM PROCESSING

Automatic ProcessingDevelopment: 80° for 1.5minFixation: 1.5minWashed: 30secDried: 30sec

NBQ

Radiographic images that are too dark are the result of all the following EXCEPT:

a. Overdevelopment

b. Film Fog

c. Non-exposure to x-rays

d. Hot temperature of solution

e. Over active chemicals

NBQ

Radiographic images that are too dark are the result of all the following EXCEPT:

a. Overdevelopment

b. Film Fog

c. Non-exposure to x-rays

d. Hot temperature of solution

e. Over active chemicals

NBQWhich of the following are purposes of the fixing solution in processing radiographs?

1. Soften emulsion

2. Harden Emulsion

3. Develop exposed silver halide salts

4. Remove undeveloped silver halide salts

 

a. 1 and 2

b. 1 and 4

c. 2 and 3

d. 2 and 4

e. 3 and 4

NBQWhich of the following are purposes of the fixing solution in processing radiographs?

1. Soften emulsion

2. Harden Emulsion

3. Develop exposed silver halide salts

4. Remove undeveloped silver halide salts

 

a. 1 and 2

b. 1 and 4

c. 2 and 3

d. 2 and 4

e. 3 and 4

NBQ

A major difference between automatic and manual processing of radiographs is that automatic processing

a. Is more expensive

b. Provides better quality films

c. Allows more latitude in exposure techniques

d. Requires special solutions at higher temperatures

NBQ

A major difference between automatic and manual processing of radiographs is that automatic processing

a. Is more expensive

b. Provides better quality films

c. Allows more latitude in exposure techniques

d. Requires special solutions at higher temperatures

FILM PROCESSING

DarkroomLight-tightSafelighting

○ Low-wattage bulb○ Safelight filter: removes short wavelengths in

blue-green, permits red-orange light○ Min. of 4 feet from film & working area○ Can still cause film fogging w/long exposure

FILM PROCESSING

Under-Developed = White Over-Developed = Dark Under-Fixed = Cloudy, Yellow-Brown

FILM PROCESSING Underdeveloped

Film appears lightInadequate development time or tempDepleted / contaminated developer solution

OverdevelopedFilm appears darkExcess development time or temperatureConcentrated developer solution

Reticulation of EmulsionFilm appears crackedSudden temp change between the developer solution

and the water bath

FILM PROCESSING

Chemical Contamination ErrorsDeveloper spots

○ Dark spots on film○ Developer solution contacts film before processing

Fixer spots○ White spots on the film○ Fixer solution contact film before processing

Air bubbles○ White spots, air trapped on the film surface after being

placed into processing solutionsYellow-brown stains

○ Exhausted chemicals, insufficient rinsing, incomplete fixation

Air Bubbles

Yellow Brown Stains

FILM PROCESSING

Film Handling ErrorsOverlapped films

○ White or black areas on film○ Appearance depends if happens in developer or fixer

Static electricity○ Thin, black branching lines○ Occurs when a packet is opened quickly

Slightly bent film○ Elongated roots○ Film may be bent to accommodate pt’s anatomy, such

as in the area of the ant maxillaSeverely bent film

○ Diagonal black line○ Film bent too severely to accommodate patient

Static Electricity

What’s wrong with this? How did this happen?

What’s wrong with this? How did this happen?

What’s wrong with this? How did this happen?

What’s wrong with this? How did this happen?

FILM PROCESSING

Film Handling ErrorsFingernail artifact

○ Black crescent-shaped marks○ Emulsion damaged by fingernails

Fingerprint artifact○ Black fingerprint○ Touching film

Scratched film○ White lines on film○ Soft emulsion removed from the film by a sharp

objectRoller marks: dirty rollers

Roller Marks

FILM PROCESSING

Lighting ErrorsLight leak

○ Exposed area appears blackFogged film

○ Film appears gray and lacks image detail and contrast

○ Improper safelight, outdated films, improper film storage, contaminated solutions

FILM PROCESSING Operator Errors

Pt not biting all way on block○ Air space seen or lack of apices

Tipped film○ Images are tipped to one side

Cone-cut○ Unexposed area on film○ Central ray not in center of film

Cervical burnout○ May appear as dental caries, radiolucent○ Radiolucent artifact seen in areas of different

densities

TECHNIQUEParalleling Technique

XCP technique (extension cone paralleling)RT-angle techniqueLong-cone techniquePrinciples

○ Film is placed in the mouth parallel to the long axis of the tooth○ Central ray of the x-ray beam directed perpendicular to the film

and long axis of the tooth○ Film holder must be used○ To achieve parallelism the film should be placed away from the

tooth and towards the middle of the oral cavity○ Object-film distance is increased○ To compensate for magnification: target-film distance is

increased

TECHNIQUE

Bisecting TechniqueBisecting-angle technique or short-cone

techniquePrinciples

○ Film is placed along lingual surface○ Tooth & film form an angle

Visualize a plane that bisects this angleCentral ray is directed perpendicular to

this imaginary bisector○ Film holders are optional

TECHNIQUEBisecting Technique: Angulation

1. HorizontalPosition of the tubehead in a side-to-side planeCentral ray directed through the contact areas of the teethIncorrect position results in overlapped contact areas (horz

overlap)

2. VerticalPositioning in the up & down planeForeshortened images: Teeth appear shortened, too much

vert angulationElongated images: teeth appear longer, not enough vert

angulation

TECHNIQUELocalization Techniques

Purpose & Use○ 2-D of 3-D object○ Does not depict B-L relationship○ Used to locate: foreign bodies, impacted teeth, unerupted

teeth, retained roots, root positions, salivary stones, jaw fractures, broken needles & instruments, filling materials

Buccal Object Rule○ 2 films at diff angulations○ 1 w/normal angulation and 2nd changing either vert or horz

angles○ Object seen in 2nd film moves in same direction as the

shift of the PID, the object is positioned to the lingual

TECHNIQUE

Take 2 radiographs at 2 different angles can determine if an object is buccal or lingual to together teeth in the archSLOB Rule: Same lingual, opposite buccalThe lingual object moves in the same direction

as the tubeheadThe buccal object moves in the opposite

direction as the tubehead

TECHNIQUE Exposure Problems

Unexposed film○ Film appears clear

Film exposed to light○ Film appears black

Overexposed film○ Film appears dark

Underexposed film○ Film appears light

NBQ

If the object film distance was too great during exposure, then which of the following technical errors is most likely to appear on a processed radiograph?

a. Cone cut

b. Elongation

c. Magnification

d. Foreshortening

e. Proximal overlapping

NBQ

If the object film distance was too great during exposure, then which of the following technical errors is most likely to appear on a processed radiograph?

a. Cone cut

b. Elongation

c. Magnification

d. Foreshortening

e. Proximal overlapping

NBQ

Another maxillary anterior PA is attempted by the dental hygienist and this time the roots of #7-10 are elongated. How would the hygienist go about correcting this error?

a. Increase vertical angulation

b. Decrease vertical angulation

c. Increase horizontal angulation

d. Decrease horizontal angulation

NBQ

Another maxillary anterior PA is attempted by the dental hygienist and this time the roots of #7-10 are elongated. How would the hygienist go about correcting this error?

a. Increase vertical angulation

b. Decrease vertical angulation

c. Increase horizontal angulation

d. Decrease horizontal angulation

TECHNIQUE

Technique Errors: PA’sIncorrect film placementAbsence of apical structuresDropped film cornerAngulation problemsIncorrect horz angulationIncorrect vert angulationCone cut

TECHNIQUE

Technique Errors: BWX’sIncorrect film placementIncorrect horz angulation (horz overlap)Incorrect vert angulationCone cut

TECHNIQUE

Miscellaneous ErrorsFilm bendingFilm creasingIncorrect positioning of pt’s fingerDouble exposureMovementReversed films

Panoramic Basic Concepts

Shows a wide view of the upper and lower jaws on a single film

Extraoral: film is positioned outside the bodyBoth film & tubehead rotate around the patient

Purpose & UseEval impacted teethEval eruption patters, growth, developmentDetect diseases, lesions, conditions of the jawsEval extent of large lesionsEval trauma

Panoramic

FundamentalsTomography

○ Tomo = section○ Radiographic technique that allows the

imaging of one layer or section of the body while blurring images from structures in other places

Focal trough○ Image is clearest

Panoramic

ProsField sizeSimplicityPatient cooperationMinimal exposure

ConsImage qualityFocal trough limitationsDistortionEquipment cost

Panoramic

Patient positioningStraight vertebral columnEnd-to-end tooth position (bite block)Midsagital plane: imaginary line that divides

face into LF-RT, perpendicular to floorFrankfort plane: imaginary plane that passes

the top of the ear canal and the bottom of the eye socket, parallel to the floor

Tongue to roof of mouth

What happened?

What happened?

What’s wrong with this picture?

Panoramic

Ghost ImageRadiopaque artifact seen on a pano filmProduced when a radiodense object is

penetrated twice by the x-ray beamSeen on opposite side of the filmIndistinct, larger and higher image

Panoramic

Common ErrorsTongue & Lip Positioning

○ Lips should be closed: dark shadow obscures ant teeth

○ Tongue against palate: dark shadow obscures the apices of maxillary teeth

Panoramic

Common ErrorsFrankfort Plane

○ Chin too high: reverse smile line, downward curve, max incisors blurred, condyles off to side of image

○ Chin too low: exaggerated smile line or jack-o-lantern, curved upward, mand incisors blurred, condyles may not be visible, condyles off top of image

What is the issue here?

Panoramic

Common ErrorsPositioning of Teeth

○ Too far anterior: ant teeth skinny / out of focus○ Too far posterior: ant teeth fat / out of focus

Midsagital Plane○ Head not centered left-to-right○ Teeth unequally magnified○ One side (side closest to film) smaller○ Other side (side farthest from film) larger

Positioning of Spine○ Pt’s spine must be straight: radiopacity in center of

film

What happened?

RADIOGRAPHIC INTERPRETATION Definition: types of bone

Cortical (compact) bone○ Sense outer layer of bone○ Radiopaque

Cancellous○ Soft spongy inner bone○ Composed of trabeculae that forms a lattice-

like network of inter-communicating spaces filled w/ bone marrow

RADIOGRAPHIC INTERPRETATION

Definitions: prominencesProcess: marked prominence or projectionRidge: linear prominence or projection of

boneSpine: sharp, thorn-like projection of boneTubercle: small bump or nodule of boneTuberosity: rounded prominence of bone

RADIOGRAPHIC INTERPRETATION

Definitions: depressionsCanal: tube-like passageway through bone

that contains nerves and blood vesselsForamen: opening or hole in bone that

permits the passage of nerves and blood vessels

Fossa: broad, shallow, scooped-out or depressed area of bone

Sinus: hollow space, cavity or recess in bone

RADIOGRAPHIC INTERPRETATION

MiscSeptum: boney wall or partition that divides

2 spaces or cavities, radiopaqueSuture: immoveable joint that represents a

line of union between adjoining bones of the skull, thin radiolucent line

LANDMARKS: MAXILLAIncisive foramen (nasopalatine)

Median palatal suture

Nasal cavity (fossa)

Canine fossa

Nasal septum

Floor of nasal cavity

Anterior nasal spine

Inferior nasal conchae

Maxillary sinus and floor max sinus

Maxillary tuberosity

Hamulus

Zygomatic process maxilla

Zygoma

LANDMARKS: MANDIBLE

Genial tubercles

Nutrient canals

Mental ridge

Mental fossa

Mental foramen

Mylohyoid ridge

Mandibular canal

Internal oblique ridge

External oblique ridge

Submandibular fossa

Coronoid process

LANDMARKS: PANO MAXILLAMastoid process of temporal bone

Styloid process

External auditory meatus

Glenoid fossa (mand fossa)

Articular eminence (tubercle)

Max tuberosity

Infraorbital foramen

Orbit

Incisive canal and foramen

Anterior nasal spine

Nasal cavity, septum

Hard palate

Max sinus

Zygomatic process of maxilla

Zygoma

Hamulus

LANDMARKS: PANO MANDIBLE

Mandibular condyle

Coronoid notch

Coronoid process

Mandibular foramen

Lingula

Mandibular canal

Mental foramen

Hyoid bone

Mental ridge

Mental fossa

Genial tubercle

Inferior border mandible

Mylohyoid ridge

Internal/External Oblique Ridge

Angle of mandible

LANDMARKS: PANO AIR SPACES

Palatoglossal air space

Nasopharyngeal air space

Glossopharyngeal air space

X-Ray Landmarks##14

##7##12

##8##11 ##12 ##7##4

##9##10

##13

##5 ##6 ##1 ##2 ##3##5 ##5

1. Lingual Foramen2. Genial tubercles3. 3-unit bridge4. Palate5. Mandibular Canal6. Mental Foramen7. Maxillary Sinus8. Coronoid process9. Third molar10.Mastoid air cells11.Articular eminence12.Pterygomaxillary fissures13.Lateral pterygoid plate14.Orbital floor

ANSWERS

8

6

72

121315

3

412 13

6

14

1

1059

511

1. Mandibular Foramen2. Styloid Ligament3. Palate4. Nasal fossa5. Hyoid bone6. Air space7. External oblique ridge8. Internal oblique ridge9. 3-unit bridge10.Angle of mandible11.Ramus12.Condyle13.Mandibular notch14.Coronoid process15.Retention ortho wire

ANSWERS

1. Anterior Nasal Spine2. Nasal Fossa3. #13 root canal & crown4. #14 with root canal &

crown5. #2 with crown6. Max sinus7. Trabeculae8. Zygomatic process of

maxilla9. Nasopalatine Foramen10.Median palatine suture

9

10

2

10

1

3 4

77

65

8 6

7

1. Recent extraction site

2. Implant Abutment3. Molar with root

canal4. Maxillary sinus5. Root apex6. Zygomatic process7. Maxillary tuberosity

#5

6

7

I

1. Possible periapical abscess

2. Lamina dura3. PDL4. Inferior border of

mandible5. Mandibular Canal

1

44

2

3

5

1